Methods for studying C13 at natural abundance by Fourier transform NMR are being developed and applied to various types of molecules. Infrared and Raman spectroscopic studies and normal coordinate analysis of 1-methyluracil and related chemical and isotopic derivatives are being conducted in order to obtain a complete vibrational assignment of this molecule. Studies of interactions and gel formation in nucleotides and polynucleotides by 1H and C13 NMR are in progress.